Endoscope and manufacturing method of endoscope

ABSTRACT

An endoscope which promotes downsizing and cost reduction, and a manufacturing method of an endoscope are provided. For this reason, in an endoscope, a lens unit containing a lens in a lens tube, an image capturing element of which an image capturing surface is covered with element cover glass, and an adhesive resin fixing the lens unit of which an optical axis of the lens is coincident with the center of the image capturing surface to the element cover glass with a separation portion are disposed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an endoscope and a manufacturing methodof an endoscope, and in particular, relates to a small diameterendoscope which promotes downsizing and cost reduction, and for example,is used for surgery, and a manufacturing method of an endoscope.

2. Description of the Related Art

In the related art, an endoscope for capturing an image of an internalbody of a patient, and an inner portion of an instrument or a structurehas become widespread in a medical field or an industrial field. In aninsertion portion of such an endoscope which is inserted into an innerportion of an observation target, light from an image capturing portionforms an image on a light receiving surface of an image sensor by anobjective lens system, and the image forming light is converted into anelectric signal and transmitted to an external image processing deviceor the like through a signal cable as a projected image signal. In ahard portion disposed in a leading end of such an endoscope, a pluralityof components such as an image capturing element, and an opticalelement, for example, a lens forming a light image on an image capturingsurface of the image capturing element is arranged. Recently, in anendoscope having such a complicated configuration, it is important tomore easily manufacture the endoscope and to further decrease an outerdiameter for reducing a burden of a person to be treated.

For example, in Japanese Patent. Unexamined Publication No. 3-12124, anelectronic endoscope forms a concave portion in a substrate, andincludes a solid image capturing element in the concave portion. Aconductive line is installed between the solid image capturing elementand an upper surface side of a step portion in the substrate. Theconductive line portion is sealed with a resin, and a glass plate isadhered to the light receiving surface of the solid image capturingelement. A frame is disposed on the substrate by being secured incontact with an outside portion from a connection portion of theconductive line. Then, the frame is secured to a barrel of an objectivelens.

In the electronic endoscope having the configuration described above,the glass plate is bonded to the light receiving surface of the solidimage capturing element, the frame is secured in contact with thesubstrate, and the barrel of the objective lens is secured to the frame.Accordingly, a reduction in a diameter of the insertion portion and areduction in a length of a leading end hard portion in an axis directionare promoted.

In the above-described electronic endoscope of an example of the relatedart, the frame is secured to the substrate, and the frame is secured tothe barrel of the objective lens, and thus a diameter greater than orequal to that of the solid image capturing element is required, and itis difficult to reduce the diameter. In addition, the number ofcomponents increases, and thus the cost also increases.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an endoscope whichpromotes downsizing and cost reduction, and a manufacturing method of anendoscope.

According to an aspect of the present invention, there is provided anendoscope including a lens unit containing a lens in a lens tube; animage capturing element including an image capturing surface which iscovered with element cover glass; and an adhesive resin fixing the lensunit in which an optical axis of the lens is coincident with the centerof the image capturing surface to the element cover glass with aseparation portion.

According to another aspect of the present invention, there is provideda manufacturing method of an endoscope including applying a UVthermosetting resin to at least one of a lens unit and an imagecapturing element; supporting the lens unit; positioning an optical axisof the lens unit and the center of an image capturing surface of theimage capturing element by referring to an image captured by the imagecapturing element while moving the image capturing element supported onan XYZ stage, and positioning a direction along the optical axis of thelens unit and the image capturing element; temporarily fixing the lensunit to the image capturing element with the UV thermosetting resin byultraviolet irradiation; and then permanently fixing the lens unit tothe image capturing element with the UV thermosetting resin by heattreatment.

According to the aspects of the present invention, it is possible topromote downsizing and cost reduction in an endoscope.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an entire configuration diagram of an endoscope system usingan endoscope according to an exemplary embodiment of the presentinvention;

FIG. 2 is a perspective view illustrating a configuration of a leadingend portion of the endoscope of this exemplary embodiment;

FIG. 3 is a cross-sectional view of a leading end portion of anendoscope according to a first exemplary embodiment;

FIG. 4 is a perspective view illustrating a configuration of a portionexcluding a mold resin from the leading end portion of the endoscopeaccording to the first exemplary embodiment;

FIG. 5 is a perspective view illustrating a configuration of a leadingend portion of an endoscope according to a second exemplary embodiment;

FIG. 6A is a cross-sectional view of a configuration according to athird exemplary embodiment in which a separation portion is filled withan adhesive resin;

FIG. 6B is a cross-sectional view of a configuration according to afourth exemplary embodiment in which an air layer is disposed in aseparation portion;

FIG. 7A is a cross-sectional view of a leading end portion of anendoscope according to a fifth exemplary embodiment;

FIG. 7B is an enlarged view of a main part of the leading end portion ofthe endoscope according to the fifth exemplary embodiment;

FIG. 8 is a cross-sectional view illustrating a configuration of aleading end portion of an endoscope according to a sixth exemplaryembodiment;

FIG. 9 is a cross-sectional view illustrating a configuration of aleading end portion of an endoscope according to a seventh exemplaryembodiment;

FIG. 10A is a configuration diagram of a position adjustment jig in afirst example of a manufacturing method of an endoscope;

FIG. 10B is a side view at the time of fixing a lens unit to an imagecapturing element in the first example;

FIG. 10C is an explanatory diagram of a projected image at the time ofperforming positioning in an XY direction in the first example;

FIG. 10D is an explanatory diagram of a projected image at the time ofperforming positioning in a Z direction in the first example;

FIG. 11A is a configuration diagram of a camera attached positionadjustment jig in a second example of the manufacturing method of anendoscope;

FIG. 11B is a side view at the time of fixing a lens unit to an imagecapturing element in the second example;

FIG. 11C is an explanatory diagram of a projected image at the time ofperforming positioning using a second camera in the second example;

FIG. 11D is an explanatory diagram of a projected image at the time ofperforming positioning using a first camera in the second example; and

FIG. 11E is an explanatory diagram of a projected image at the time ofperforming positioning in a Z direction in the second example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments (hereinafter, referred to as “thisexemplary embodiment”) of an endoscope and a manufacturing method of anendoscope according to the present invention will be described in detailwith reference to the drawings.

FIG. 1 is an entire configuration diagram of an endoscope system usingan endoscope according to an exemplary embodiment of the presentinvention. FIG. 2 is a perspective view illustrating a configuration ofa leading end portion of the endoscope of this exemplary embodiment.FIG. 3 is a cross-sectional view of a leading end portion of anendoscope according to a first exemplary embodiment. FIG. 4 is aperspective view illustrating a configuration of a portion excluding amold resin from the leading end portion of the endoscope according tothe first exemplary embodiment.

In FIG. 1, an entire configuration of endoscope system 13 includingendoscope 11 and video processor 19 is illustrated as a perspectiveview. In FIG. 2, a configuration of leading end portion 15 of endoscope11 illustrated in FIG. 1 is illustrated as a perspective view. In FIG.3, a configuration of leading end portion 15 illustrated in FIG. 2 isillustrated as a cross-sectional view. In FIG. 4, a configurationexcluding mold resin 17 from leading end portion 15 illustrated in FIG.2 is illustrated as a perspective view.

Furthermore, a direction herein which is used for description accords toa direction illustrated in each drawing. Here, “Up” and “Down”respectively correspond to an upper portion and a lower portion of videoprocessor 19 placed on a horizontal plane, and “front (head)” and “back”respectively correspond to a leading end side of insertion portion 21and a base end side of plug portion 23 in an endoscope main body(hereinafter, referred to as “endoscope 11”).

As illustrated in FIG. 1, endoscope system 13 includes endoscope 11which is a flexible scope used for medical purposes, and video processor19 which performs known image processing or the like with respect to astill image and a moving image obtained by capturing an image of aninner portion of an observation target (here, a human body). Endoscope11 extends in an approximately front and back direction, and includesinsertion portion 21 which is inserted into the inner portion of theobservation target, and plug portion 23 to which a back portion ofinsertion portion 21 is connected.

Video processor 19 includes socket portion 27 which is opened in frontwall 25 of video processor 19. The back portion of plug portion 23 ofendoscope 11 is inserted into socket portion 27, and thus endoscope 11is able to transmit and receive electric power and various signals (aprojected image signal, a control signal, and the like) to and fromvideo processor 19.

The above-described electric power and the various signals are led tosoft portion 29 from plug portion 23 through transmission cable 31(refer to FIG. 3) inserted into an inner portion of soft portion 29.Image data output by image capturing element 33 disposed in leading endportion 15 is transmitted to video processor 19 from plug portion 23through transmission cable 31. Then, video processor 19 performs imageprocessing such as color correction, and tone correction with respect tothe received image data, and outputs the image processed image data to adisplay device (not illustrated). The display device, for example, is amonitor device including a display device such as a liquid crystaldisplay panel, and displays an image of a photographic subject capturedby endoscope 11.

As illustrated in FIG. 3, endoscope 11 according to this exemplaryembodiment includes lens unit 35, image capturing element 33, andadhesive resin 37 in leading end portion 15. Lens unit 35 contains alens in lens tube 39. Image capturing surface 41 of image capturingelement 33 is covered with element cover glass 43. Capacitor forelectrostatic countermeasure 45 is attached to a surface of imagecapturing element 33 opposite to element cover glass 43. Adhesive resin37, for example, is configured of a UV thermosetting resin. Adhesiveresin 37 fixes lens unit 35 in which an optical axis of the lens iscoincident with the center of image capturing surface 41 to elementcover glass 43 with separation portion 47. Accordingly, lens unit 35 isdirectly adhered and fixed to image capturing element 33 by adhesiveresin 37. In order to obtain final hardness, for example, it isnecessary that adhesive resin 37 is subjected to a heat treatment, andadhesive resin 37 is an adhesive agent which is cured until hardness dueto ultraviolet irradiation is obtained.

Insertion portion 21 includes flexible soft portion 29 of which a backend is connected to plug portion 23, and leading end portion 15 which iscontinued to a leading end of soft portion 29. Soft portion 29 has asuitable length corresponding to need such as various endoscopicinspections and endoscope surgeries. The largest outer diameter ofleading end portion 15, for example, is approximately 1.5 mm.

As illustrated in FIG. 3, leading end portion 15 includes imagecapturing element 33, and tubular lens tube 39 including the lens or thelike, and includes lens unit 35 supporting image capturing element 33 ona back end, and circuit substrate 49 mounted on a back portion of imagecapturing element 33. Lens tube 39, for example, is formed of metal, andleading end portion 15 includes the hard portion by using a hardmaterial in lens tube 39.

Transmission cable 31 is electrically connected to a back portion ofcircuit substrate 49, and a connection portion of circuit substrate 49is covered with mold resin 17 for sealing. Furthermore, in the followingdescription, a term of “adhesive agent” does not strictly indicate asubstance used for adhering a surface to a surface of a solid substance,but widely indicates a substance which is able to be used for couplingtwo substances, or a substance having a function as a sealing materialwhen a cured adhesive agent has high barrier properties with respect togas and liquid.

In lens tube 39, a plurality of (in an illustrated example, three)lenses L1 to L3 which are formed of an optical material (glass, a resin,or the like), and diaphragm member 51 which is interposed between lensL1 and lens L2 are embedded in a state where the plurality of lenses L1to L3 and diaphragm member 51 are closely in contact with each other ina direction of optical axis LC. Lens L1 and lens L3 are fixed to aninner circumferential surface of lens tube 39 over the entirecircumference by an adhesive agent. A front end of lens tube 39 ishermetically closed (sealed) by lens L1, and a back end is hermeticallyclosed by lens L3, and thus an inner portion of lens tube 39 is notinvaded by air, moisture, or the like. Accordingly, air or the like isnot able to be pulled from one end of lens tube 39 to the other end.Furthermore, in the following description, lenses L1 to L3 arecollectively referred to as optical lens group LNZ.

As a metal material configuring lens tube 39, for example, nickel isused. Nickel has a comparatively high rigidity modulus and highcorrosion resistance, and is suitable as a material configuring leadingend portion 15. Instead of nickel, for example, a copper nickel alloymay be used. A copper nickel alloy also has high corrosion resistance,and is suitable as a material configuring leading end portion 15. Inaddition, as the metal material configuring lens tube 39, a materialwhich is able to be manufactured by electrocasting (electroplating) ispreferably selected. Here, the reason for using electrocasting isbecause dimensional accuracy of a member manufactured by theelectrocasting is extremely high at less than 1 μm (so-called sub-micronaccuracy), and variation is also reduced at the time of manufacturing aplurality of members. As described later, lens tube 39 is an extremelysmall member, and an error in inner and outer diameter dimensionsaffects optical performance (image quality) of endoscope 11. Lens tube39, for example, is configured of an electrocasted nickel tube, and thuseven if the diameter is reduced, endoscope 11 is obtained in which highdimensional accuracy is able to be ensured, and an image having highimage quality is able to be captured.

As illustrated in FIG. 3 and FIG. 4, image capturing element 33, forexample, is configured of an image capturing device such as a smallCharge Coupled Device (CCD) or a small Complementary Metal-OxideSemiconductor (CMOS) which is in the shape of a square when seen fromthe front and back directions. Light incident from the outside forms animage on image capturing surface 41 of image capturing element 33 byoptical lens group LNZ in the lens tube. Circuit substrate 49 mounted inthe back portion (a rear surface side) of image capturing element 33 hasan outer shape which is slightly smaller than image capturing element 33when seen from a back side. Image capturing element 33, for example,includes a Land Grid Array (LGA) in a rear surface, and is electricallyconnected to an electrode pattern formed on circuit substrate 49.

In addition, as illustrated in FIG. 2, in endoscope 11, the entire imagecapturing element 33 and at least a part of lens unit 35 on imagecapturing element 33 side are covered with mold resin 17.

Next, a modification example in which a part of the configuration ofendoscope 11 is changed will be described as another exemplaryembodiment.

FIG. 5 is a perspective view illustrating a configuration of a leadingend portion of an endoscope according to a second exemplary embodiment.In the second exemplary embodiment, a first modification example of theconfiguration of leading end portion 15 of the endoscope illustrated inFIG. 3 and FIG. 4 is illustrated.

In order to improve the strength of four corners of image capturingelement 33, as illustrated in FIG. 5, adhesive resin 37 is additionallydisposed in the endoscope of the second exemplary embodiment. In thiscase, image capturing element 33 is positioned in a back end of lensunit 35, and then adhesive resin 37 is applied to four portions (in FIG.5, three portions among the four portions are illustrated) facing cornerportions of image capturing element 33 in a back end portion of lensunit 35 which are in contact with image capturing element 33. In thisstate, an applied portion of adhesive resin 37 is exposed, and adhesiveresin 37 is cured by ultraviolet irradiation for a short period of timesuch as a few seconds, and thus it is possible to reduce the timerequired for a process. According to the configuration of the firstmodification example, strength of an adhesion portion between imagecapturing element 33 and lens unit 35 increases.

FIGS. 6A and 6B are diagrams illustrating a third exemplary embodimentand a fourth exemplary embodiment as another modification example of theleading end portion of the endoscope, FIG. 6A is a cross-sectional viewof a configuration according to a third exemplary embodiment in which aseparation portion is filled with an adhesive resin, and FIG. 6B is across-sectional view of a configuration according to a fourth exemplaryembodiment in which an air layer is disposed in a separation portion.The third exemplary embodiment illustrates a second modification exampleof the configuration of the leading end portion of the endoscope, andthe fourth exemplary embodiment illustrates a third modification exampleof the configuration of the leading end portion of the endoscope.

In the endoscope of the third exemplary embodiment (the secondmodification example), as illustrated in FIG. 6A, separation portion 47between lens unit 35 and element cover glass 43 is filled with adhesiveresin 37. As in an illustrated example, when a final surface of lens L3on an image capturing side includes a concave surface in a surfacefacing element cover glass 43, a space between a flat surface of elementcover glass 43 and the concave surface of lens L3, for example, isfilled with adhesive resin 37 having light transmissivity such astransparence. In this case, a distance between edge portion 55 of a lenscircumferential edge of second surface L3R2 of lens L3 and element coverglass 43, for example, is 0 to 100 μm. In the configuration of thesecond modification example, it is possible to further improve thestrength of the adhesion portion by being filled with adhesive resin 37.Furthermore, a final surface of lens L3 on the image capturing sidewhich is a surface facing element cover glass 43 may include a convexsurface. When the convex surface is included, the distance between acenter portion of second surface L3R2 of lens L3 and element cover glass43, for example, is 0 to 100 μm.

In the endoscope of the fourth exemplary embodiment (the thirdmodification example), as illustrated in FIG. 6B, air layer 53 isdisposed in separation portion 47 between lens unit 35 and element coverglass 43. As in an illustrated example, when the final surface of lensL3 on the image capturing side includes the concave surface in thesurface facing element cover glass 43, air layer 53 is formed between aflat surface of element cover glass 43 and the concave surface of lensL3 without being filled with adhesive resin 37. In this case, thedistance between edge portion 55 of the lens circumferential edge ofsecond surface L3R2 of lens L3 and element cover glass 43, for example,is 0 to 100 μm. In the configuration of the fourth exemplary embodiment,a refractive index difference in the final surface of lens unit 35 onthe image capturing side increases by disposing air layer 53, andfreedom for designing the lens increases.

FIGS. 7A and 7B are diagrams illustrating a configuration of a leadingend portion of an endoscope according to a fifth exemplary embodiment,FIG. 7A is a cross-sectional view of the leading end portion, and FIG.7B is an enlarged view of a main part of FIG. 7A. The fifth exemplaryembodiment illustrates a fourth modification example of theconfiguration of the leading end portion of the endoscope.

In the endoscope of the fifth exemplary embodiment (the fourthmodification example), the final surface of lens L3 of lens unit 35 onthe image capturing side is formed to be flat. As in an illustratedexample, when the final surface of lens L3 on the image capturing sideis configured by a flat surface, lens unit 35 faces element cover glass43 with a predetermined distance, adhesive resin 37 is applied thicklyto an outer circumferential portion, and thus lens unit 35 is adheredand fixed to element cover glass 43. Here, a distance of separationportion 47 between lens unit 35 and element cover glass 43, for example,is 10 μm to 40 μm according to an error in optical design.

FIG. 8 is a cross-sectional view illustrating a configuration of aleading end portion of an endoscope according to a sixth exemplaryembodiment. The sixth exemplary embodiment illustrates a fifthmodification example of the configuration of the leading end portion ofthe endoscope.

The endoscope of the sixth exemplary embodiment (the fifth modificationexample) illustrates another configuration example of lens L3 of lensunit 35. In lens unit 35, first surface L1R1 of lens L1 includes aconcave surface, second surface L1R2 includes a flat surface, firstsurface L2R1 of lens L2 includes a flat surface, second surface L2R2includes a convex surface, first surface L3R1 of lens L3 which is afinal lens includes a concave surface, and second surface L3R2 which isthe final lens includes a convex surface in the order from thephotographic subject side to the image capturing side.

Separation portion 47 between second surface L3R2 of lens L3 which isthe convex surface and element cover glass 43 is filled with adhesiveresin 37. According to adhesive resin 37, lens unit 35 is directlyadhered and fixed to image capturing element 33. Adhesive resin 37 isconfigured of a transparent adhesive resin material, and when arefractive index of adhesive resin 37 is nad, and a refractive index oflens L3 is n3, for example, a material satisfying a relationship of|n3−nad|>0.01 is used. That is, the refractive index nad of adhesiveresin 37 has as great refractive index difference as possible comparedto the refractive index n3 of lens L3 of an end portion on the imagecapturing side, and specifically, for example, a refractive index nadhaving a difference greater than 0.01 is preferable. For example, whenthe refractive index n3 of lens L3 is 1.55, as adhesive resin 37, amaterial having a refractive index nad of 1.52 is used. Furthermore,when the refractive index difference is able to be ensured, a magnituderelationship between the refractive index n3 of lens L3 and therefractive index nad of adhesive resin 37 may be reversed.

In addition, an interval of separation portion 47 between second surfaceL3R2 of lens L3 and image capturing surface 41 of image capturingelement 33, for example, is 0 to 100 μm in a protruding portion of thecenter portion of the convex surface of second surface L3R2. That is,the interval is in a dimension range from a state where the centerportion of second surface L3R2 is in contact with image capturingsurface 41 to a state of being separated by 100 μm. Accordingly, adistance between lens unit 35 and image capturing element 33 in theoptical axis direction is adjusted within a range of 0 to 100 μm, andfocus position adjustment (focusing) is performed, and thus it ispossible to make installation easy.

In addition, at least a part of lens unit 35 on the image capturingside, an outer circumferential portion of image capturing element 33,and the vicinity of the connection portion of transmission cable 31 onthe leading end side are sealed by, for example, mold resin 17 havinglight blocking properties such as a black color as a resin member forsealing. A connection fixation portion between lens unit 35 and imagecapturing element 33 has a double structure covering an outercircumferential portion of adhesive resin 37 having light transmissivityof a transparent material or the like which transmits light rays of aphotographic subject image by disposing mold resin 17 having lightblocking properties such as a black color.

In the sixth exemplary embodiment, a refractive index difference betweenlens L3 and adhesive resin 37 is greater than 0.01, and thus arefraction effect in second surface L3R2 of lens L3 increases.Accordingly, refractive power is able to be obtained by allowing secondsurface L3R2 of lens L3 which is the final surface of optical lens groupLNZ on the image capturing side to effectively function, and the numberof optical surfaces which are able to be used in optical lens group LNZincreases. As a result thereof, with respect to an optical performance(resolution, chromatic aberration, distortion, or the like) of opticallens group LNZ, it is possible to reduce the number of lenses forobtaining a necessary optical performance and to promote downsizing andcost reduction. In addition, second surface L3R2 of lens L3 is theconvex surface, and adhesive resin 37 is adhered to a curved surface,and thus a contact area of adhesive resin 37 increases and it ispossible to improve adhesion strength. In addition, by using the doublestructure of adhesive resin 37 having light transmissivity and moldresin 17 having light blocking properties, it is possible to improvedurability and strength of the leading end portion of the endoscope. Inaddition, the interval of separation portion 47 in a center portion oflens L3 is 0 to 100 μm, and thus a thickness dimension tolerance of eachcomponent of lens unit 35 in the optical axis direction, and aninstallation dimension tolerance between lens unit 35 and imagecapturing element 33 are able to be mitigated, assemblability is able tobe improved, and the component cost is also able to be reduced.

FIG. 9 is a cross-sectional view illustrating a configuration of aleading end portion of an endoscope according to a seventh exemplaryembodiment. The seventh exemplary embodiment illustrates a sixthmodification example of the configuration of the leading end portion ofthe endoscope.

The endoscope of the seventh exemplary embodiment (the sixthmodification example) illustrates still another configuration example oflens L3 of lens unit 35. In lens unit 35, first surface L1R1 of lens L1includes a concave surface, second surface L1R2 includes a flat surface,first surface L2R1 of lens L2 includes a flat surface, second surfaceL2R2 includes a convex surface, first surface L3R1 of lens L3 which isthe final lens includes a convex surface, and second surface L3R2 whichis the final surface includes a concave surface in order from thephotographic subject side to the image capturing side. That is, in thisconfiguration example, the concavity and convexity of lens L3 isreversed from that of the sixth exemplary embodiment illustrated in FIG.8. Here, only a portion having a configuration different from that ofthe sixth exemplary embodiment will be described.

Separation portion 47 between second surface L3R2 of lens L3 which isthe concave surface and element cover glass 43 is filled with adhesiveresin 37. The interval of separation portion 47, for example, is 0 to100 μm in a peripheral portion of the concave surface of second surfaceL3R2, that is, an edge portion of a lens circumferential edge of secondsurface L3R2. That is, the interval is in a dimension range from a statewhere the peripheral portion of second surface L3R2 is in contact withimage capturing surface 41 to a state of being separated by 100 μm.

According to the seventh exemplary embodiment, similar to the sixthexemplary embodiment, a refractive index difference between lens L3 andadhesive resin 37 is greater than 0.01, and thus it is possible toreduce the number of lenses for obtaining a necessary opticalperformance, and it is possible to promote downsizing and costreduction. In addition, second surface L3R2 of lens L3 is the concavesurface, and adhesive resin 37 is adhered to a curved surface, and thusa contact area of adhesive resin 37 increases and it is possible toimprove adhesion strength. In addition, the interval of separationportion 47 in the peripheral portion of lens L3 is 0 to 100 μm, and thusa thickness dimension tolerance of each component of lens unit 35 in theoptical axis direction, and an installation dimension tolerance betweenlens unit 35 and image capturing element 33 are able to be mitigated,assemblability is able to be improved, and the component cost is alsoable to be reduced.

Furthermore, in the sixth exemplary embodiment illustrated in FIG. 8 andin the seventh exemplary embodiment illustrated in FIG. 9, similar tothe fourth exemplary embodiment illustrated in FIG. 6B, the air layermay be disposed in a center portion of the lens by adhering only aperipheral portion of lens L3 by the adhesive resin. In this case, it ispossible to obtain sufficient refractive power in second surface L3R2 oflens L3 regardless of a refractive index of the adhesive resin.

Here, an example of dimensions of the endoscope of this exemplaryembodiment is illustrated. Furthermore, the following numerical valuesindicate one specific example, and various examples are consideredaccording to use applications, usage environments, or the like.

As an example, lens unit 35 has a length of S=1.4 mm in the front andback direction. In addition, a cross-sectional surface of lens tube 39is in the shape of a circle having an outer diameter of D=1.00 mm and aninner diameter of d=0.90 mm. In this case, a thickness of lens tube 39in a diameter direction is (D−d)/2=50 μm. In addition, image capturingelement 33 is in the shape of a square of which one side has a length ofT=1.00 mm when seen from a front surface, and image capturing surface 41in the shape of a square when seen from the front surface is disposed ina center portion.

Here, a circle of an outer circumference (an outer diameter=D) of lenstube 39 is approximately in internal contact with a square of imagecapturing element 33, and is in external contact with a square of imagecapturing surface 41. Then, positions of the center of image capturingsurface 41 (an intersection point of diagonal lines of image capturingsurface 41), the center of lens unit 35 (the center of a circle of aninner circumference of lens unit 35), and the center of lens tube 39(the center of the circle of the outer circumference of lens tube 39)are coincident with each other, and optical axis LC passes therethrough.More accurately, a normal line passing through the center of imagecapturing surface 41 is optical axis LC, and lens unit 35 is positionedwith respect to image capturing element 33 such that optical axis LCpasses through the center of lens unit 35.

Next, coating of each of lenses L1, L2, and L3 of lens unit 35 in thefirst to the seventh exemplary embodiments will be described.

In order to prevent a decrease in light intensity or an occurrence offlare and ghost, a thin film of a single layer or a multi-layer isdeposited on the surface of the lens. As a material of the thin film, ametal oxide such as titanium oxide (TiO₂), tantalum pentoxide (Ta₂O₅),hafnium oxide (HfO₂), zirconium oxide (ZrO₂), and aluminum oxide(Al₂O₃), metal such as silver (Ag), aluminum (Al), and nickel (Ni),silicon oxide (SiO₂), silicon carbide (SiC), silicon (Si), magnesiumfluoride (MgF₂), and the like are used. In addition, generally, in anoutermost layer of the single layer or the multi-layer, magnesiumfluoride is used in order to obtain an antifouling effect of theoutermost surface. However, in the first to the seventh exemplaryembodiments, second surface L3R2 which is the final surface of lens L3which is the final lens is fixed to image capturing element 33 byadhesive resin 37, and when magnesium fluoride is coated to theoutermost surface, adhesion strength significantly decreases. For thisreason, in the outermost surface of second surface L3R2 of lens L3, ametal oxide, metal, silicon oxide, silicon carbide, silicon, and thelike are preferably used in addition to magnesium fluoride.

In addition, by using a silane coupling agent such as trimethylsilane(C₃H₁₀Si) which chemically couples an inorganic material and an organicmaterial together in the outermost surface of second surface L3R2 oflens L3, adhesion strength between lens L3 of the inorganic material andadhesive resin 37 of the organic material may increase.

Next, a manufacturing method (a manufacturing process of leading endportion 15) of endoscope 11 of this exemplary embodiment having theconfiguration described above will be described.

FIGS. 10A and 10B are diagrams illustrating a first example of amanufacturing method of an endoscope, FIG. 10A is a configurationdiagram of a position adjustment jig, FIG. 10B is a side view at thetime of fixing the lens unit to the image capturing element, FIG. 10C isa diagram illustrating a projected image at the time of performingpositioning in an XY direction, and FIG. 10D is an explanatory diagramof a projected image at the time of performing positioning in a Zdirection. Furthermore, here, the XY direction indicates right-left andup-down directions illustrated in FIG. 1, and the Z direction indicatesthe front and back direction illustrated in FIG. 1.

In the first example of the manufacturing method of an endoscope, byusing position adjustment jig 57, a back end of lens unit 35 is fixed tobe blocked by image capturing element 33. Position adjustment jig 57includes sensor support portion 59, first XYZ stage 61, lens unitsupport portion 63, second XYZ stage 65, flat surface base 67, and testchart 69.

Sensor support portion 59 supports a lower surface of image capturingelement 33. First XYZ stage 61 maintains sensor support portion 59 andis able to perform position adjustment in the front-back and right-leftdirections and the up and down direction (it is preferable to use amicrostage). Lens unit support portion 63 horizontally supports lensunit 35 from both side surfaces. Second XYZ stage 65 maintains lens unitsupport portion 63 and is able to perform position adjustment in thefront-back and right-left directions and the up and down direction. Testchart 69 is a photographic subject of lens unit 35, and has a pattern towhich vignetting and a focus of the photographic subject image due toimage capturing is able to refer. Flat surface base 67 commonly supportstest chart 69, and sensor support portion 59 and lens unit supportportion 63.

Leading end portion 15 is assembled by using position adjustment jig 57described above, and basically, leading end portion 15 is manuallyassembled by an operator using a microscope.

First, adhesive resin 37 is applied to at least one of lens unit 35 andimage capturing element 33 in advance. Then, lens unit 35 is supported,and the optical axis of lens unit 35 and the center of image capturingsurface 41 of image capturing element 33 are positioned with referenceto an image captured by image capturing element 33 while moving imagecapturing element 33 supported on first XYZ stage 61. Specifically, forexample, as illustrated in FIG. 10C, the center of lens tube 39 and lensL3, and projected image center 71 are positioned. The projected image ofimage capturing element 33 is obtained by placing a probe (notillustrated) on a terminal of image capturing element 33 to extract animage signal, and by displaying the image on a display device (notillustrated).

Subsequently, a direction along the optical axis of lens unit 35 andimage capturing element 33 is positioned. In this positioning step, asillustrated in FIG. 10D, by adjusting a position of lens unit 35 in thefront and back direction, incident light from test chart 69 is focusedon image capturing surface 41 of image capturing element 33. That is, asillustrated in FIG. 10B, focusing is performed by adjusting the positionof lens unit 35 in a direction of optical axis LC.

At the time of performing the position adjustment of lens unit 35,transmission cable 31 and circuit substrate 49 may be or may not beconnected to each other. When transmission cable 31 and circuitsubstrate 49 are not connected to each other, as described above, theprobe is placed on the terminal of image capturing element 33 to extractthe image signal, and thus a photographic subject image for a test isdisplayed on the display device.

On the other hand, when transmission cable 31 is connected to imagecapturing element 33, an output of image capturing element 33 isprocessed by video processor 19 described above, and thus the image isable to be displayed on the display device. By using a predeterminedtest chart 69 (for example, a resolution chart) as the photographicsubject, the position adjustment of lens unit 35 is easily performed,and it is possible to reduce the time required for the positioning step.

In a step where the position adjustment of lens unit 35 and imagecapturing element 33 is completed, it is preferable that adhesive resin37 is slightly exposed from a space between lens unit 35 and imagecapturing element 33. When an amount of adhesive resin 37 is notsufficient, adhesive resin 37 is injected into the space between lensunit 35 and image capturing element 33. The space between lens unit 35and image capturing element 33 is filled with the injected adhesiveresin 37 by a capillary action.

After positioning image capturing element 33 on the back end of lensunit 35, adhesive resin 37 is cured by ultraviolet irradiation, and lensunit 35 is temporarily fixed to image capturing element 33 by adhesiveresin 37. The ultraviolet irradiation is performed with respect to theexposed adhesive resin 37 in a state where a relative front and backposition of lens unit 35 and image capturing element 33 is maintained.Adhesive resin 37 is cured by the ultraviolet irradiation, and thusimage capturing element 33 is temporarily fixed in the vicinity of theback end of lens unit 35. Adhesive resin 37 is cured by the ultravioletirradiation for a short period of time such as a few seconds, and thusit is possible to reduce the time required for a process. Lens unit 35and image capturing element 33 which are temporarily fixed are detachedfrom position adjustment jig 57.

After that, adhesive resin 37 is further cured by heat treatment, andlens unit 35 and image capturing element 33 are permanently fixed byadhesive resin 37. Adhesive resin 37 is cured by the heat treatment, andthus lens unit 35 and image capturing element 33 are strongly fixed.

Subsequently, leading end portion 15 is subjected to mold processing bywhich the back portion of lens unit 35 and image capturing element 33are covered with mold resin 17. In a mold processing step, mold resin 17is applied and secured to lens unit 35 in order to cover at least imagecapturing element 33 positioned on a back side from the back end of lensunit 35, and circuit substrate 49 and the leading end of transmissioncable 31 (an electric connection portion with respect to image capturingelement 33), and thus a sealing portion is configured.

At this time, mold resin 17 is also applied to the back end of lens unit35 across the front surface of image capturing element 33, and thusseparation portion 47 is reliably blocked. Mold resin 17 used herein hashigh viscosity to the extent of covering at least image capturingelement 33, circuit substrate 49, the leading end of transmission cable31, and a gap, and is applied mainly for sealing by which moisture isprevented from invading the inner portion of leading end portion 15 fromthe back side from image capturing element 33 and separation portion 47.

In addition, in order to easily produce an illustrated shape by usingmold resin 17, the sealing portion may be formed by using a resin mold.In this case, the resin mold (not illustrated) is arranged to cover fromthe back end of lens unit 35 to the leading end of transmission cable 31in advance, mold resin 17 is casted and cured, and the resin mold isremoved.

As mold resin 17, various known adhesive agents are able to be used, andfor example, an adhesive agent of a thermosetting resin such as an epoxyresin and an acrylic resin may be used. Further, it is preferable toadopt a black resin containing carbon particles in these resins.Accordingly, it is possible to prevent stray light from the outside frombeing incident on image capturing surface 41 of image capturing element33.

After that, leading end portion 15 is placed under an environment of 60°C. to 80° C. for approximately 30 minutes, and thus mold resin 17covering image capturing element 33, circuit substrate 49, the leadingend of transmission cable 31, and separation portion 47 is completelycured. When the mold processing step is finished, assembling of leadingend portion 15 of endoscope 11 is completed.

FIGS. 11A and 11B are diagrams illustrating a second example of themanufacturing method of an endoscope, FIG. 11A is a configurationdiagram of a camera attached position adjustment jig, FIG. 11B is a sideview at the time of fixing the lens unit to the image capturing element,FIG. 11C is an explanatory diagram of a projected image at the time ofperforming positioning using a second camera, FIG. 11D is an explanatorydiagram of a projected image at the time of performing positioning usinga first camera, and FIG. 11E is an explanatory diagram of a projectedimage at the time of performing positioning in the Z direction.Furthermore, the same reference numeral is applied to the same member asthe member illustrated in FIGS. 10A to 10D, and the repeated descriptionwill be omitted. Similar to the first example, the XY directionindicates the right-left and up-down directions illustrated in FIG. 1,and the Z direction indicates the front and back direction illustratedin FIG. 1.

In the second example of the manufacturing method of an endoscope, byusing camera attached position adjustment jig 73, the back end of lensunit 35 is fixed to be blocked by image capturing element 33. Cameraattached position adjustment jig 73 includes a first moving image cameraattached microscope (hereinafter, referred to as “first camera 77”)observing image capturing element 33 from a front side, and a secondmoving image camera attached microscope (hereinafter, referred to as“second camera 75”) observing lens unit 35 from a back side.

First camera 77 and second camera 75 are integrated with each other andare able to simultaneously capture right and left images (or up and downimages, and front and back images). Hereinafter, such a camera having anintegrated configuration is referred to as “right and left camera 79”.An image capturing direction is different approximately 180 degrees in astate where optical axes of the respective first camera 77 and secondcamera 75 are aligned with each other with extremely high accuracy.Right and left camera 79 is attached to second XYZ stage 65, and isarranged between sensor support portion 59 of the camera attachedposition adjustment jig 73 and lens unit support portion 63. Sensorsupport portion 59 is supported on first XYZ stage 61. First XYZ stage61, second XYZ stage 65, and lens unit support portion 63 are disposedin flat surface base 67. Test chart 69 is attached to flat surface base67.

In camera attached position adjustment jig 73, parallelism betweensensor support portion 59 supported on first XYZ stage 61 and lens unitsupport portion 63 is adjusted in advance, and is aligned with highaccuracy. Furthermore, at the time of mounting image capturing element33, a bottom surface of image capturing element 33 is temporarily fixedto sensor support portion 59. As a method of temporarily fixing thebottom surface, for example, image capturing element 33 may be vacuumsucked by forming a plurality of micropores in sensor support portion59, and by connecting the micropores to a vacuum pump.

Leading end portion 15 is assembled by using camera attached positionadjustment jig 73 described above, and basically, leading end portion 15is manually assembled by the operator using a microscope. First,adhesive resin 37 is applied to at least one of lens unit 35 and imagecapturing element 33 in advance.

Then, as illustrated in FIG. 11A, right and left camera 79 includingfirst camera 77 and second camera 75 of which the optical axes arecoincident with each other is arranged between image capturing element33 and lens unit 35. Subsequently, as illustrated in FIG. 11D, thecenter of image capturing surface 41 of image capturing element 33 ismoved to projected image center 71 with reference to a projected imagecaptured by first camera 77. Then, as illustrated in FIG. 11C, thecenter of lens unit 35 is moved to projected image center 71 withreference to a projected image captured by second camera 75. After that,as illustrated in FIG. 11B, after right and left camera 79 is retracted,as illustrated in FIG. 11E, the distance between lens unit 35 and imagecapturing element 33 in the direction along the optical axis is adjustedwith reference to a projected image captured by image capturing element33.

In the positioning step, a position of second XYZ stage 65 is adjustedwith reference to a projected image obtained by capturing an image ofthe back end of lens unit 35 by second camera 75, and thus right andleft camera 79 (accurately, the optical axis of right and left camera79) is aligned with the center of lens unit 35 (a center position in thediameter direction). A right and left position of first XYZ stage 61 isadjusted with reference to a projected image captured by first camera77, and thus the center of image capturing surface 41 of image capturingelement 33 supported on sensor support portion 59 is moved to the centerof XY coordinates on a screen, that is, the center position of lens unit35. Accordingly, even when the center of image capturing surface 41 ofimage capturing element 33, that is optical axis LC varies according tosolid, lens unit 35 and image capturing element 33 are able to bepositioned on the basis of optical axis LC.

Then, right and left camera 79 is retracted from a space between sensorsupport portion 59 and lens unit support portion 63, the front and backposition of first XYZ stage 61 is adjusted, and image capturing element33 supported on sensor support portion 59 is in contact with the backend of lens unit 35.

After, image capturing element 33 is positioned on the back end of lensunit 35 by the operation described above, similar to the first example,an applied portion of adhesive resin 37 which is exposed is irradiatedwith ultraviolet rays, and adhesive resin 37 is cured, and thus lensunit 35 is temporarily fixed to image capturing element 33 by adhesiveresin 37. Thus, image capturing element 33 is positioned and thenmounted on the back end of lens unit 35.

After that, similar to the first example, by performing heat treatment,lens unit 35 is permanently fixed to image capturing element 33 byadhesive resin 37. Subsequently, similar to the first example, the moldprocessing is performed, and the assembling of leading end portion 15 ofendoscope 11 is completed.

Next, an action of endoscope 11 of this exemplary embodiment having theconfiguration described above will be described.

In endoscope 11 according to this exemplary embodiment, lens unit 35 isfixed to image capturing element 33 by adhesive resin 37 in a statewhere a predetermined distance is maintained. In fixed lens unit 35 andimage capturing element 33, the optical axis of lens unit 35 and thecenter of image capturing surface 41 are positioned. In addition, thedistance between lens unit 35 and image capturing element 33 ispositioned to be a distance in which incident light through lens unit 35from the photographic subject is focused on image capturing surface 41of image capturing element 33. Lens unit 35 and image capturing element33 are positioned and then fixed.

Separation portion 47 is formed between fixed lens unit 35 and imagecapturing element 33. Lens unit 35 and image capturing element 33 arerelatively positioned, and are fixed to each other by adhesive resin 37,and thus the shape of separation portion 47 is determined. That is,separation portion 47 is an adjustment gap for positioning lens unit 35and image capturing element 33. The adjustment gap may not be included.In the specific example of the dimension described above, an adjustmentis performed at least from approximately 30 μm to approximately 100 μm.At this time, a tolerance is ±20 μm. Accordingly, the minimum adjustmentgap of this case is 10 μm.

In endoscope 11, after separation portion 47 is the adjustment gap andthe positioning of lens unit 35 and image capturing element 33 iscompleted, separation portion 47 is used for a fixed space of adhesiveresin 37. Accordingly, lens unit 35 is able to be directly fixed toimage capturing element 33. Accordingly, an interposing member such as aframe or a holder for fixing lens unit 35 to image capturing element 33which has been required in the related art is not required. In addition,the frame, the holder, or the like is able to be omitted, and thus thenumber of components is reduced, and a fixed structure is simplified.Accordingly, the diameter of leading end portion 15 of endoscope 11 isable to be decreased, and even when a reduction in the diameter ispromoted, leading end portion 15 is able to be configured in the minimumdimensions. In addition, the component cost is also able to be reduced.Further, the number of interposing components at the time of fixing lensunit 35 to image capturing element 33 decreases, and thus it is possibleto reduce the number of man-hours required for the operations relevantto the positioning and the fixing, and it is possible to easily performthe positioning with high accuracy. In addition, it is possible toreduce the manufacturing cost, and it is possible to improveproductivity.

In addition, in endoscope 11, the entire image capturing element 33 iscovered with mold resin 17. More specifically, mold resin 17 also coversan external portion of transmission cable 31 connected to imagecapturing element 33. Mold resin 17 also covers at least a part of lensunit 35 (an adjacent portion with respect to image capturing element33). The expression “at least” indicates that mold resin 17 may coverthe entire outer circumference of lens tube 39. Mold resin 17 coversimage capturing element 33 and lens unit 35, and thus also continuouslycovers separation portion 47 therebetween. Accordingly, mold resin 17 iscontinuously formed across image capturing element 33 and lens unit 35,and thus contributes to an increase in fixation strength between imagecapturing element 33 and lens unit 35. In addition, mold resin 17 alsoincreases airtightness, liquidtightness, and light blocking propertiesof separation portion 47. Further, mold resin 17 also increases lightblocking properties when an optical fiber for light guidance isembedded.

In addition, in endoscope 11, element cover glass 43 is fixed to a lightemitting surface of the lens on the image capturing element side byadhesive resin 37. Accordingly, lens unit 35 is fixed to image capturingelement 33 by adhesive resin 37 with high strength.

Adhesive resin 37 has light transmissivity, and it is preferable that arefractive index of adhesive resin 37 is close to that of air. When a UVthermosetting resin is used as adhesive resin 37, an outer portion ofthe filled adhesive agent is able to be cured by ultravioletirradiation, and an inner portion of the filled adhesive agent which isnot able to be irradiated with ultraviolet rays is able to be cured byheat treatment.

In addition, in endoscope 11, when the light emitting surface of thelens facing element cover glass 43 is a concave surface, annularcross-sectional surface (an edge portion) 55 around the lens is adheredto element cover glass 43. At this time, the outer circumference of thelens, and the outer circumference of lens tube 39 may be simultaneouslyfixed by adhesive resin 37. Air layer 53 is disposed between the lensand image capturing element 33, and thus it is possible to improve anoptical performance of the lens. For example, it is possible to increasea refractive index of emitted light from the lens to air layer 53.Accordingly, resolution increases, and thus an optical design such asincreasing a field angle is facilitated. As a result thereof, imagequality is improved.

In a first manufacturing method of endoscope 11 according to thisexemplary embodiment, lens unit 35 and image capturing element 33 arepositioned according to the output of image capturing element 33 byusing position adjustment jig 57, and an additional camera forpositioning or the like is not used. Thus, it is possible to directlyuse the projected image obtained by image capturing element 33, and thusit is possible to easily perform position adjustment. Then, it ispossible to directly fix lens unit 35 to image capturing element 33which are positioned. Accordingly, it is possible to decrease the numberof man-hours of a fixation operation, and it is possible to reduceoperation time. In addition, it is possible to perform positioning ofhigh accuracy without interposing a plurality of members.

In a second manufacturing method of endoscope 11 according to thisexemplary embodiment, the image of each of lens unit 35 and imagecapturing element 33 is captured, and lens unit 35 and image capturingelement 33 are positioned by using the camera attached positionadjustment jig 73. Accordingly, even when the center of image capturingsurface 41 of image capturing element 33, that is the optical axisvaries according to the solid, lens unit 35 and image capturing element33 are able to be positioned on the basis of the optical axis of rightand left camera 79.

As described above, according to endoscope 11 and the manufacturingmethod of endoscope 11 according to this exemplary embodiment, it ispossible to promote downsizing, cost reduction, and productivityimprovement.

According to the examples described above, after the separation portionis the adjustment gap and the positioning of the lens unit and the imagecapturing element is completed, the separation portion is used for thefixed space of the adhesive resin. Accordingly, the lens unit is able tobe directly fixed to the image capturing element. Accordingly, theinterposing member such as the frame or the holder for fixing the lensunit to the image capturing element which has been required in therelated art is not required. In addition, the number of components isreduced, and the fixed structure is simplified. In addition, the numberof interposing components decreases, and thus it is possible to reducethe number of man-hours required for the fixation operation, and it ispossible to easily perform the positioning with high accuracy. As aresult thereof, it is possible to reduce the diameter of the leading endportion of the endoscope. In addition, it is possible to reduce themanufacturing cost, and it is possible to improve productivity.

According to the examples described above, the entire image capturingelement is covered with the mold resin. More specifically, the moldresin also covers the external portion of the transmission cableconnected to the image capturing element. The mold resin also covers atleast a part of the lens unit (the adjacent portion with respect to theimage capturing element). The expression “at least” indicates that themold resin may cover the entire outer circumference of the lens tube.The mold resin covers the image capturing element and the lens unit, andthus also continuously covers the separation portion therebetween.Accordingly, the mold resin is continuously formed across the imagecapturing element and the lens unit, and thus contributes to an increasein fixation strength between the image capturing element and the lensunit. In addition, the mold resin also increases airtightness,liquidtightness, and light blocking properties of the separationportion. Further, the mold resin also increases light blockingproperties when the optical fiber for light guidance is embedded.

According to the examples described above, the element cover glass isfixed to the light emitting surface of the lens on the image capturingelement side by the adhesive resin. Accordingly, the lens unit is fixedto the image capturing element by the adhesive resin with high strength.As the adhesive resin, an adhesive resin having light transmissivity anda refractive index close to that of air is used. In this case, as theadhesive resin, a UV thermosetting resin is preferably used. Accordingto the UV thermosetting resin, the inner portion of the filled adhesiveagent which is not able to be irradiated with ultraviolet rays is ableto be cured by heat treatment.

According to the examples described above, when the light emittingsurface of the lens facing the element cover glass is a concave surface,the annular cross-sectional surface around the lens is adhered to theelement cover glass. At this time, the outer circumference of the lens,and the outer circumference of the lens tube may be simultaneously fixedby the adhesive resin. The air layer is disposed between the lens andthe image capturing element, and thus it is possible to improve anoptical performance of the lens. For example, it is possible to increasea refractive index of the emitted light from the lens to the air layer.Accordingly, resolution increases, and thus the optical design such asincreasing a field angle is facilitated. As a result thereof, imagequality is improved.

According to the examples described above, the concave surface or theconvex surface of the final surface of the lens unit has refractivepower, and thus it is possible to reduce the number of lenses forobtaining a necessary optical performance, and it is possible to promotedownsizing and cost reduction. In addition, the adhesive resin isadhered to the curved surface, and thus a contact area of the adhesiveresin increases and adhesion strength is improved.

According to the examples described above, refractive power is able tobe obtained by allowing the concave surface or the convex surface of thefinal surface of the lens unit to effectively function, and the numberof optical surfaces which are able to be used in the optical lens groupincreases, and thus it is possible to reduce the number of lenses forobtaining a necessary optical performance and to promote downsizing andcost reduction.

According to the examples described above, a thickness dimensiontolerance of each component of the lens unit in the optical axisdirection, and an installation dimension tolerance between the lens unitand the image capturing element is able to be mitigated, and thusassemblability is able to be improved, and the component cost is alsoable to be reduced.

According to the examples described above, when the lens unit is fixedto the image capturing element by the adhesive resin, it is possible toprevent adhesion strength from being decreased.

According to the examples described above, the additional camera forpositioning or the like is not used by using the output of the imagecapturing element. It is possible to easily perform the positionadjustment by directly using the projected image obtained by the imagecapturing element. Then, it is possible to directly fix the lens unitand the image capturing element which are used for obtaining theprojected image. Accordingly, it is possible to decrease the number ofman-hours of a fixation operation, and it is possible to reduceoperation time. It is possible to perform positioning of high accuracywithout interposing a plurality of members.

According to the examples described above, even when the center of theimage capturing surface of the image capturing element, that is, theoptical axis varies according to the solid, the lens unit and the imagecapturing element are able to be positioned on the basis of the opticalaxis of the right and left camera.

As described above, various exemplary embodiments are described withreference to the drawings, but the present invention is not limited tosuch an example. It is obvious that a person skilled in the art is ableto conceive various change examples or correction examples in a categorydescribed in the Claims, and it is understood that these change examplesor correction examples naturally belong to the technical range of thepresent invention. In addition, the respective constituents in theexemplary embodiment described above may be arbitrarily combined withina range not deviating from the gist of the invention.

What is claimed is:
 1. An endoscope, comprising: a lens unit containinga lens in a lens tube, the lens including an optical axis; an imagecapturing element including an image capturing surface which is coveredwith an element cover glass, the optical axis of the lens beingcoincident with a center of the image capturing surface; an adhesiveresin fixing an image capturing element side of the lens in the lensunit to the element cover glass and fixing an image capturing elementside of the lens tube to the element cover glass, the adhesive resinbeing a light transmitting material; a separation portion between thelens unit and the element cover glass; and a mold resin covering theimage capturing element and at least a part of the lens unit, the moldresin being a light blocking material.
 2. The endoscope of claim 1,wherein the separation portion is filled with an adhesive resin.
 3. Theendoscope of claim 1, wherein an air layer transmitting light from thelens is disposed in the separation portion.
 4. The endoscope of claim 1,wherein the image capturing element side of the lens includes a concavesurface or a convex surface.
 5. The endoscope of claim 4, wherein theseparation portion is filled with the adhesive resin, and a refractiveindex of the lens and a refractive index of the adhesive resin have arefractive index difference greater than or equal to a predeterminedvalue.
 6. The endoscope of claim 4, wherein the lens unit is adhered andfixed to the image capturing element with a distance of a predeterminedrange in an optical axis direction in the separation portion.
 7. Theendoscope of claim 1, wherein an outermost surface of the lens on theimage capturing element side of the lens is magnesium fluoride.
 8. Theendoscope of claim 1, wherein an outermost surface of the lens on theimage capturing element side of the lens is any one of a metal oxide,metal, silicon oxide, silicon carbide, and silicon.
 9. The endoscope ofclaim 1, wherein an outermost surface of the lens on the image capturingelement side of the lens is a silane coupling agent.
 10. A manufacturingmethod of an endoscope, comprising: applying a UV thermosetting resin toat least one of a lens unit containing a lens in a lens tube, the lensincluding an optical axis, and an image capturing element which includesan image capturing surface covered with an element cover glass;supporting the lens unit; positioning the optical axis of the lens unitand a center of the image capturing surface of the image capturingelement by referring to an image captured by the image capturing elementwhile moving the image capturing element supported on an XYZ stage;adjusting a position of the lens unit relative to the image capturingelement along the optical axis of the lens unit; temporarily fixing thelens unit to the image capturing element with the UV thermosetting resinby ultraviolet irradiation; permanently fixing an image capturingelement side of the lens in the lens unit to the element cover glass ofthe image capturing element and permanently fixing an image capturingside of the lens tube to the element cover glass of the image capturingelement with the UV thermosetting resin by heat treatment, the heattreated UV thermosetting resin being a light transmitting material; andcovering the image capturing element and at least a part of the lensunit with a mold resin, the mold resin being a light blocking material.11. A manufacturing method of an endoscope, comprising: applying a UVthermosetting resin to at least one of a lens unit containing a lens ina lens tube, the lens including an optical axis, and an image capturingelement which includes an image capturing surface covered with anelement cover glass; arranging a right and left camera including a firstcamera and a second camera of which optical axes are coincident witheach other between the image capturing element and the lens unit; movingthe center of an image capturing surface of the image capturing elementonto the center of a screen by referring to a projected image capturedby the first camera; moving the center of the lens unit onto the centerof the screen by referring to a projected image captured by the secondcamera; adjusting a distance in a direction along the optical axis ofthe lens unit and the image capturing element by referring to aprojected image captured by the image capturing element after retractingthe right and left camera; temporarily fixing the lens unit to the imagecapturing element with the UV thermosetting resin by ultravioletirradiation; permanently fixing an image capturing element side of thelens in the lens unit to the element cover glass of the image capturingelement and permanently fixing an image capturing side of the lens tubeto the element cover glass of the image capturing element with the UVthermosetting resin by heat treatment, the heat treated UV thermosettingresin being a light transmitting material; and covering the imagecapturing element and at least a part of the lens unit with a moldresin, the mold resin being a light blocking material.